This invention pertains to stylus switches, for example for use with digitizing tablets and write-on image displays.
Prior art stylus switches are known for use with, for example, digitizing tablets and write-on image displays. Such prior art styli used with digitizing tablets employ a "pen down" switch which requires a noticeable pressure to actuate, and which requires considerable travel (typically about 0.01 to 0.02 inch) in order to actuate. Such a prior art stylus is generally used with a CRT monitor located some distance away from the digitizing tablet. Since the operator cannot watch the CRT and the digitizing tablet simultaneously, the stylus location is shown on the CRT by means of a cursor regardless of whether the "pen down" switch is actuated or not. The "pen down" switch is generally used only to issue a command.
Commands are issued by the operator through the stylus in two steps: First, the operator places the stylus on the digitizing tablet and moves it around until the cursor is at the desired location on the CRT. Then the operator depresses the "pen down" switch on the stylus which issues the command. For this type of application, it is useful to have a "pen down" switch which requires significant pressure and travel to actuate, since this avoids inadvertent "pen down" indication.
For an application such as a digitizer integrated with a display, there is no need for a cursor, since the display appears on the surface of the digitizing tablet. The "pen down" switch is only used to indicate that the stylus is touching the display. The stylus may be used to draw, print, write, erase, or to issue a command. In this case, the "pen down" switch should have no noticeable travel, and should require no more pressure to activate than would be required to write with a pen or pencil. Prior art styli are not suitable for this application, since the pressure required to maintain "pen down" indication causes operator fatigue Furthermore, prior art styli require the operator to hold the stylus in a substantially vertical direction in order to properly actuate the "pen-down" switch. While this may be suitable for issuing commands, it is awkward and fatiguing for the operator, and is not very practical for use when it is desired that the stylus be used to allow the computer to receive an operator's drawing or handwriting.